Patent DE-102008022495-A1 (DE)
Title: Device for producing object by layerwise construction from powdered metallic or ceramic material, comprises housing with process chamber, support for layer construction, irradiation device, powder layer preparation device, and gear unit
Inventor: FOCKELE MATTHIAS
IPC: B22F3/105
Filed: 2008-05-07
Abstract: The device comprises a housing (4) with a process chamber (2), a support for the layer construction and for providing a construction zone (20) in the process chamber, an irradiation device for irradiating the material powder layer prepared on the support in a cross-sectional area of the model of the object associated with the layer with a focused laser radiation, which causes the material powder to melt or optionally sinter in the cross-sectional area under the effect of heat, and a powder layer preparation device (16), which comprises a movable carrier element (14) and a powder dispenser. The device comprises a housing (4) with a process chamber (2), a support for the layer construction and for providing a construction zone (20) in the process chamber, an irradiation device for irradiating the material powder layer prepared on the support in a cross-sectional area of the model of the object associated with the layer with a focused laser radiation, which causes the material powder to melt or optionally sinter in the cross-sectional area under the effect of heat, a powder layer preparation device (16), which comprises a movable carrier element (14) and a powder dispenser provided in the carrier element, and a gear unit. The powder dispenser has a powder delivery apparatus movable relative to the carrier element. A movement drive of the powder delivery apparatus is mechanically derivable from a movement drive of the carrier element. The gear unit intervenes the mechanical drive of the powder delivery apparatus by the movement of the movable carrier element and comprises two gear element groups interacting with one another. One of the gear element groups is assigned to the process chamber and is stationary relative to the process chamber and the other gear element group is assigned to the layer preparation device and is connected with the carrier element. One gear element group comprises a toothed rack and the other gear element group comprises a toothed wheel. The teeth of the toothed rack and the toothed wheel are formed in the form of pins with a circular cross-section. The carrier element is movable in a linear back and forth pivoting movement over the construction zone by pivoting around a vertical pivoting axis. The toothed rack is designed, so that the teeth of the toothed rack are arranged in a tooth plane parallel to a plane of the pivoting movement of the carrier element along a segment of a circular line. The center point of the circle coincides with the intersection point of the tooth plane and the pivoting axis. The powder delivery apparatus comprises a dosing shaft, which is rotatable around its longitudinal axis. The longitudinal axis of the dosing shaft is connected with the gear element group assigned to the layer preparation device. The gear element group assigned to the process chamber has toothed racks, which are spatially distributed, so that the dosing shaft rotates itself around a given angle due to the reciprocal effect between the two gear element groups if the carrier element moves over a given part of the total paths, along whose carrier element moves itself during its movement over the construction zone. The dosing shaft is inserted into a recess at a base of the powder dispenser, so that a part of its surface is always turned to, and directly contacts with the interior of the powder dispenser and other part of its surface is always turned to a base of the process chamber. The dosing shaft has a dosing receiver at its surface in the form of a dosing groove. A portion of material powder is to be removed from the interior of the dispenser if the dosing receiver is turned to the interior of the dispenser and a portion of the material powder is to be delivered over the construction zone if the dosing receiver is turned to the construction zone. The number of dosing receivers, the distribution of the dosing receivers around the longitudinal axis of the dosing shaft and the angle, around which the dosing shaft is rotated in the back and forth movement, are selected, so that a given number of portions of material powder are delivered over the construction zone in each back and forth movement.